Pathology is a crucial basis in the process of restoration of historical monuments. So as just by an accurate pathology, a correct and effective restoration plan will be achieved. Amongst the various and different types of damages occurring in the historic monuments, Structural cracks in the walls are very important and considered as special issues that can endanger the stability and structural balance and speed up the process of destruction. These cracks are caused by disruptions in the stability and balance of walls and each disruptive factor usually leads to one crack. However, in some cases, after occurring instability and cracks in a wall by a disruptive factor, it can be seen that with the growth of cracks, secondary and new cracks have been formed. Therefore it is always the question that what kinds of changes in the static equilibrium of the wall and secondary cracks are due to the formation of the first cracks. Therefore in answer to this question, the study aimed to analyze the formation of secondary cracks in the walls without openings. The method is theoretical and static analysis and it is tried to provide examples through a field study to verify the results. According to the studies, secondary cracks do not occur when ordinary settlement in each of the two ends of a wall or almost the entire length of a wall occurs. Rather we see secondary cracks when the settlement has occurred in the middle of the wall or a long settlement has occurred at the beginning or end of the wall. And also the form of secondary cracks depends on the length of the settlement area in a wall and the form of the first cracks